Stabilized petroleum oil distillates



Patented June 6, 1939 AT 2;; OFFICE STABILIZED PETROLEUM on. nrsrm'ras Jacob Faust, Belleville, N. .L, assignor to L. Sonneborn Sons, Inc., a corporation of Delaware No Drawing. Application April 2, 1937, Serial No. 134,522

13. Claims.

This invention relates to stabilized petroleum oil distillates.

In the refining of petroleum oils a number of the distillates obtained are inherently subject to autoxidation and resulting deterioration which fact greatly impairs the usefulness of the products affected thereby and renders the same in many instances unit for the purposes for which they are intended. This autoxidative deterioration is particularly attendant upon the lighter cracked hydrocarbon. fractions such as kerosene, gasoline, etc. and upon some of the highly refined heavier fractions such as medicinal white oils. Thus, for instance, a cracked gasoline will gradually precipitate gummy substances which are very detrimental to its use as a motor fuel while medicinal white oils will develop a highly undesirable and objectionable rancid odor and taste. In all these cases of autoxldation of petroleum distillates the cause is substantially the same and only the manifestation of the reaction differs in each particular case.

The first stage of autoxidative deterioration of petroleum oil distillates is the formation of peroxides and the time which elapses until the first peroxide formation can be observed is regarded as a criterion of the stability of a given product. Under ordinary conditions such time element is expressed in weeks or months but by subjecting an oil distillate to high temperatures the time elapsing until the first traces of peroxide formation appear may be expressed in minutes and is then commonly termed in petroleum refining technology the induction period of the oil distillate and serves as a practical measure for the relative stability of the product. One common practice for the determination of the induction period is to heat the distillate to be tested in quantities of cc. in stoppered test tubes in an oil bath kept at 300 F. for convenient intervals, as a rule multiples of 5 minutes." The peroxide test as such may be carried out by shaking the oil to be test- 1 ed with an aqueous acetone solution of ferrous thio-cyanate which will show a red coloration at the first sign of peroxide formation as the result of the conversion of the ferrous to ferric thiocyanate. Where in the specification and claims, therefore, I use the term induction period in connection with an oil distillate inherently subject to autoxidation I mean to define thereby the period which elapses until the first traces of peroxide formation appear in the distillate while the same is heated at a temperature of approximately 300 F.

I have discovered that I can substantially stabilize petroleum oil distillates and substantially inhibit any inherent autoxidation and resulting deterioration of such products by the addition of comparatively small amounts of substances having in their molecular structure at least once the grouping s \N C/ I 5 in open chain configuration and of the general formula R1 S N-c m SR in which R1 or R2 or both may represent hydrogen or any aliphatic or aromatic or mixed aliphatic aromatic or heterocyclic radical and in which R. may represent any aliphatic or aromatic or mixed aliphatic aromatic or heterocyclic radical or any metal radical including the ammonium radical and aliphatic or aromatic or mixed aliphatic aromatic substituted ammonium radical. Substances of the aiore-described nature may be generally classified as dithiocarbamic acid compounds such as dithiocarbamic acid salts or ethers, ammonium dithiocarbamate, mono or di-alkyl-ammonium monor or di-alkyl-dithiocarbamate as well as the aryl, aralkyl, aryl-aralkyl, aryl-alkyl including heterocyclic derivatives of these products. Thus where I use in the specification and claims the term dithiocarbamic acid 30 compound or such similar expression I mean to embrace substances of the afore-described character and nature as well as mixtures thereof.

In the practical application of my invention the dithiocarbamic acid compound is added to the distillate to be treated in small amounts sufiicient to raise the normal induction period of the same and to substantially effectuate thereby a stabilization to the desired extent. Though substantially absolute and permanent stabilization may be obtained it will in many cases suflice for practical purposes to achieve a stabilization equivalent to an induction period in excess of twice the induction period of the untreated distillate. This result may be obtained by additions of 0.001% and in some cases as low as 0.0001% of the dithiocarbamic acid compound.

In manufacturing a commercial product, however, Iprefer to obtain an induction period of at least minutes which is'equivalent to a stabil- 50 ization under atmospheric conditions and even constant exposure to sunlight for a period in excess of 6 months which in most cases is regarded as sufliciently stable and I have found additions of 0.01% to 0.001% of suflicient potency for such purposes.

Concerning the method of addition of the di-' thiocarbamic acid compound I have found thatwhen the amount used is within the range of substantial solubility in the distillate, (e. g. lower concentrations), the particular mode of addition is not very critical and the substance may be added either in solid form or in the form of a solution in a suitable solvent. When, however, the amount of dithiocarbamic acid compound used is substantially beyond such range and practically within the range of substantial insolubility, (e. g. higher concentrations); I have discovered as a further embodiment of my invention that the potency of the dithiocarbamic acid compound may be greatly enhanced by adding the same to the distillate not in solid form to be suspended therein but in the form of a solution in a solvent which as between the oil distillate and the dithiocarbamic acid compound will preferentially dissolve the latter being at the same time completely miscible with the former. In this manner it is possible in most instances to obtain induction periods of twice those obtainable with dithiocarbamio acid compound suspensions. The selection of the particular solvent-used in this connection depends upon the particular dithiocarbamic acid compound used in its preferential solvent power relation to the particular distillate-sought to be treated. I have found, however, that in the majority of cases satisfactory results are obtained with a solution of the inhibitor compound in ether, alcohol or acetone. No critical limitations exist with regard to the concentration of inhibitor compounds in the preferential solvent; it is of course understood that the concentration shall be sufliciently low to prevent separation of solid inhibitor particles at low temperatures. The addition of the inhibitor in its preferential solvent solution is preferably eifected in the cold.

The following tabulations-are illustrative of practical embodiments of the invention but are in no way to be taken as indicative of the scope thereof:

TABLE I Dimethyl-ammonium dimethyl-dithiocarbamate (CH3) 2N.CSSNH2(C'H3) 2 Induction period C o n c e t r a tion of inwhite 0 White oil Kerosene Gasoline hihitor inhibitor inhibitor inhibitor inhibitor 51 min in ethereal in ethereal in ethereal p0 solution solution solution Minutes Minutes Minutes Minutes 0.1 Over 180 Over 180 Over 180 Over 160 0.01 Over 110-120 Over 180 Over 95-100 Over 120 0.001 Over 30-35 Oter -80 Over 60-65 Over 0.0001 Over 20-25 Over 35-40 Over 25-28 Over 30-35 Normal ini d u c t i o n period 10 10 3-4 10-12 TABLE II Sodium diethyl-dithiocarbamate (CzHs) zNCSSNa the induction periods of inhibitor added in preferential solution whereas the second column demonstrates induction periods of inhibitor suspensions. Amounts of 0.0001% dimethyl-ammonium dimethyl-dithiocarbamate or 0.001% sodium diethyl-dithiocarbamate respectively are practically within the range of substantial solubility in either of the distillates used and the respective induction periods do not materially diifer whether the particular inhibitor is added in .solid form or in the form of a preferential solvent solution as for instance in ether. Amounts, however in excess of 0.0001% dimethyl-ammonium dimethyldithiocarbamate or 0.001 sodium diethyl-dithiocarbamate are practically within the range of substantial insolubility in either of the distillates and additions of the respective inhibitors in preferential solvent solution result in markedly higher induction periods than corresponding additions of such inhibitors in solid form.

The foregoing description is by way of illustration and not of limitation and I am not to be limited to any details but only by the appended claims in which I have endeavored to' claim broadly all inherent novelty.

I claim:

1. A petroleum oil distillate composition comprising a petroleum oil distillate inherently subject to autoxidation having normally a low induction period and. a small amount of a dithio- 'carbamic acid compound suflicient to raise the normal induction period of said distillate said compound possessing in open chain configuration at least once the grouping 2. A petroleum oil distillate composition comprising a petroleum oil distillate inherently subject to autoxidation having normally a low induction period and a small amount of a dithiocarbamic acid compound sufiicient to raise the normal induction period of said distillate to at least twice the normal period said compound possessing in open chain configuration at least once the r up n 3. A petroleum oil distillate composition comprising a petroleum oil distillate inherently subject to autoxidation having normally an induction period of less than 50 minutes and a small amount of a. dithiocarbamic acid compound sufficient to raise the normal induction period of said distillate to at least 50 minutes said compound possessing in open chain configuration at least once the grouping 4. A petroleum oildistillate composition comprising a cracked kerosene having normally a av induction period and a small amount of a :hiocarbamic acid compound suflicient to raise e normal induction period of said kerosene said mpound possessing in open chain configuration least once the grouping s NC 5. A petroleum oil distillate composition comising a cracked gasoline having normally a low iuction period and a small amount oil a dithiorbamic acid compound sufficient to raise the rmal induction period of said gasoline, said mpound possessing in open chain configuration least once the grouping s N-C B. A petroleum oil distillate composition comising a medicinal white oil having normally a v induction period and a small amount of a dilocarbamic acid compound suificient to raise a normal induction period of said medicinallite oil said compound possessing an open chain nflguration at least once the grouping l. A petroleum oil distillate composition comising a medicinal white oil having normally a v induction period and a small amount of an :yl dithiocarbamate sumcient to raise the nor- |.l induction period of said medicinal white oil. 3. A petroleum oil distillate composition comising a medicinal white 011 having normally a v induction period and a small amount of an :yl-ammonium alkyl-dithiocarbamate suflicient raise the normal induction period of said uiicinal white 011.

10. A petroleum oil distillate composition comprising a white 011 having normally a low induction period and a small amount of a solution of a aliphatic dithiocarbamate in ether, sufiicient to raise the normal induction period of said white oil, said compound possessing in open chain configuration at least once the grouping 11. A petroleum oil distillate composition in accordance with claim 1 in which said di-thiocarbamic acid compound is an alkyl di-thiocarbamate.

12. A petroleum oil distillate composition in accordance with claim 1 in which said di-thiocarbamic acid compound is an alkyl ammonium alkyl di-thiocarbamate.

13. A petroleum oil distillate composition comprising a medicinal white oil inherently subject to autoxidation and a small amount of an aliphatic dithiocarbamate suflicient to substantially inhibit autoxidation of said medicinal white oil.

JACOB FAUST.

CERTIFICATE OF CORREGTIOIG.

Patent No. 2,166,851.

JACOB FAUST.

June 6,1939.

It is hereby certified that error appears in the printed specification or the above munbered patent requiring correctiones follows: Page 1, first column, lines, for the word "unit" read unfit; same page, second column, line 26, for "monor' read mono 3 page 5, second column, line 6, claim 9, for the word "derivative" reed compound; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the casein the Patent'Oifice.

Signed and sealed this 1st day of August, A. D. 1939.

(Seal) Henry Van Arsdele, acting Commissioner of Patents; 

